The present invention is directed to materials and methods for neutralization and decontamination of chemical and biological toxants. In particular, the present invention is directed to concentrated formulations containing solubilizing compounds and reactive compounds that can be rehydrated with water and then delivered as foams, sprays, liquids, fogs and aerosols to contaminated surfaces.
Terrorist threats, potentially involving weapons of mass destruction, are increasing both in the United States and abroad. The use, and threat of use, of chemical warfare (CW) and biological warfare (BW) agents in the context of weapons of mass destruction are of paramount concern both to national defense as well as to state and local law enforcement.
Certain CW agents known to pose a threat by terrorists share chemical characteristics that present an opportunity for the development of countermeasures. The chemical agents sarin, soman, and tabun (G-agents) are all examples of phosphorus-containing compounds which, when altered chemically, can lose their toxicity. Mustard, which is an example of the H-agents, and VX, which is an example of the V-agents, can also be altered chemically and rendered harmless. In addition, certain of the known BW agents, including botulinum toxin, anthrax and other spore-forming bacteria, vegetative bacteria, including plague, and various viruses can also be deactivated chemically.
An effective, rapid, and safe (non-toxic and non-corrosive) decontamination technology is required for the restoration of civilian facilities in the event of a domestic terrorist attack. Ideally, this technology should be applicable to a variety of scenarios such as the decontamination of open, semi-enclosed, and enclosed facilities as well as sensitive equipment. Examples of types of facilities where the decontamination formulation may be utilized include a stadium (open), an underground subway station (semi-enclosed), and an airport terminal or office building (enclosed). Many industrial applications have needs for an environmentally benign decontamination solution, including food processing plants, animal farms, hospitals, nursing homes, ambulances, etc.
The compounds that have been developed for use in detoxification of both CW and BW agents have been deployed in a variety of ways, including liquids, foams, fogs, gels, pastes, creams, and lotions. Stable aqueous foams (including xe2x80x9cstickyxe2x80x9d foams with glue added) have been used in various applications including fire fighting and law enforcement applications (such as prison riot containment). Such foams, however, have typically been made using anionic surfactants and anionic or nonionic polymers. These foams, unfortunately, have not been effective in the chemical decomposition and neutralization of most chemical and biological weapons (CBW) agents.
A new class of aqueous-based decontamination formulations, designated generically as xe2x80x9cDF-100xe2x80x9d, and a method for manufacturing DF-100, was disclosed in commonly-assigned U.S. patent application Ser. No. 09/607,586, xe2x80x9cFormulations for Neutralization of Chemical and Biological Toxantsxe2x80x9d by Tucker and Tadros, filed Nov. 1, 2000, which is herein Incorporated by Reference. Hereinafter, that application will be referred to as the ""586 application. The formulations for DF-100 have been proven effective for neutralizing both chemical and biological agents, is environmentally benign (non-toxic and non-corrosive), works on a variety of anticipated surfaces, can be rapidly deployed, requires minimal logistics support, is relatively inexpensive, and can be incorporated into a wide variety of carriers (e.g., foams, liquid sprays, fogs, mists, and aerosols).
The formulations for DF-100 comprise a cationic surfactant and a reactive compound; that when mixed with a carrier (such as water or seawater in a fluid phase) and exposed to a toxant, neutralizes the toxant. The reactive compound can be a nucleophilic or oxidizing compound or a mixture of both. Hence, the reactive compound can be both oxidizing and nucleophillic. The reactive compound can be selected from hydrogen peroxide, urea hydrogen peroxide, an activated peroxide compound (e.g., hydrogen peroxide+bicarbonate) hydroperoxycarbonate, oximates, alkoxides, aryloxides, aldehydes, peroxymonosulfate, Fenton""s reagent, and sodium hypochlorite. The cationic surfactant solubilizes the sparingly soluble toxants.
A cationic hydrotrope (an ionic-surfactant-like material with short hydrocarbon segments) can be added, which increases the solubility of the toxant in aqueous media, increases subsequent reaction rates between the reactive compound and the toxant, and significantly increases the physical stability of foams made with DF-100. Increasing the foam""s stability and liquid-holding power improves the overall effectiveness of neutralization of toxants by increasing the contact time of the decontamination solution with the toxant.
The formulations of DF-100 exploit the principles of cationic micelle catalysis and the solubilization power of cationic hydrotropes to dissolve the otherwise sparingly soluble toxants.
The principle for detoxifying chemical agents in the foam is to provide a mechanism to solubilize the sparingly soluble chemical (CW) agents, and to attract a nucleophilic agent, dissolved in aqueous media, to a position in close proximity to the agent molecule vulnerable to nucleophilic attack. This is accomplished through the recognition that certain nucleophilic agents are negatively charged. Therefore, the DF-100 solution contains cationic surfactants that form positively-charged micelles, which solubilize the CW agents and attract the negatively-charged nucleophiles, such as hydroxyl ions (OHxe2x88x92), hydroperoxide ions (OOHxe2x88x92), and hydroperoxycarbonate ions (HCO4xe2x88x92). The negatively-charged nucleophiles are formed from the addition of hydrogen peroxide to the DF-100 solution, or by reacting hydrogen peroxide with a bicarbonate salt to form the highly-reactive hydroperoxycarbonate species (a much stronger oxidant).
In the aqueous environment, the CW agent is located (i.e., solubilized) within the micelle comprises of an aggregate of surfactant molecules with hydrophobic tails forming the interior core of the micelle, and hydrophilic heads concentrating at the outer surface of the micelle. These positively-charged hydrophilic heads attract the negatively-charged nucleophiles, greatly enhancing the reaction rates with the CW agents within the micelle. In this sense, the cationic surfactant acts as a catalyst to speed up the reaction between the toxant and the reactive compound. This is contrasted with the situation that would occur in a foam constructed with anionic surfactants, such as typical firefighting foam, where the negatively-charged micelles would repel the negatively-charged nucleophiles and reduce the reaction rate.
The DF-100 formulation can also contain hydrotropes, which are ionic surfactant-like molecules with short hydrocarbon segments that are added to increase the solubility of the surfactants and the CW agents. To ensure chemical compatibility, cationic hydrotropes are used. The cationic hydrotropes also contribute by significantly increasing the rate of hydrolysis of CW agents.
With respect to neutralization of BW agents, the solubilizing compounds serves to solubilize and soften the biological agent""s outer coat, thereby exposing the biological agent""s DNA to the reactive compound. After the solubilizing compound enhances exposure of the toxant to the reactive compound, the reactive compound reacts with the toxant, either by an oxidation or hydrolysis reaction, to neutralize the toxant. For biological agents, the solubilizing compound can be a cationic surfactant, an alcohol such as a fatty alcohol, or a cationic hydrotrope.
Depending upon the concentration of the various compounds used in the formulation of DF-100, greater than 99.999% and often as much as 99.99999% (7-log kill) or more of biological toxants (including anthrax spores) can be neutralized (killed) within approximately one hour.
The DF-100 formulation can also include a bicarbonate salt (e.g., potassium, sodium, or ammonium bicarbonate). Then, if hydrogen peroxide is used as the reactive compound, the peroxide can react with the bicarbonate to form a highly reactive hydroperoxycarbonate species, which is especially effective in reacting with biological toxants to neutralize them.
The DF-100 formulation can be adjusted to optimize its ability to be deployed successfully as a foam by adding water soluble cationic polymers and/or long-chain fatty alcohols. Polymer additions increase the solution""s viscosity. Long chain fatty alcohols increase the stability of the foam against excessive liquid drainage and/or bubble collapse.
Short-chain alcohols can also be added to DF-100 to aid in solubilization, and glycol ether can be added to solubilize the fatty alcohols.
DF-100 formulations are typically xe2x80x9cactivatedxe2x80x9d by adding the reactive compound as the last step, after all of the other components have been mixed together, immediately prior to use. However, the neutralization effectiveness of activated DF-100 solution degrades rapidly with time (after only 8 hours). Hence, the pot life of an activated DF-100 solution is somewhat limited. Therefore, to extend the shelf life, DF-100 can be manufactured as a two-part, binary system (i.e., in kit form), comprising a relatively inert component (Part A) and an active ingredient (Part B) comprising the reactive compound. Part B is then added to Part A immediately prior to use, thereby maximizing the effectiveness of the activated formulation.
In a binary system, Part A comprises the relatively inert ingredients of DF-100, and, hence, has a relatively long shelf life. However, the reactive ingredients used for Part B, such as an aqueous solution of hydrogen peroxide, generally have a much shorter shelf life (hydrogen peroxide natural decomposes into water and oxygen). Storage of DF-100 as a binary system thereby usefully enables the shorter shelf life component (Part B) to be replaced more frequently, and with a lower cost than replacing the entire (i.e., activated) formulation (A+B).
The ""586 application discloses a variety of methods for manufacturing the DF-100 formulations as a binary system. In one method, hereinafter referred to as the ""586 method, the relatively inert component, Part A, is produced in a form where nearly all of the water necessary to make-up the activated DF-100 solution (A+B) has already been added to Part A during the manufacturing process. Part A subsequently has a concentration (wt %) of 87%-92%. Part A has a relatively long shelf life, and is ready for shipping and use in the field. Then, in the field, the final ingredient (reactive component Part B) is added and mixed to produce an activated DF-100 solution having a final hydrogen peroxide concentration of 0.1-4%. In the ""586 method, Part B comprises a highly concentrated, aqueous solution (30%-50%) of hydrogen peroxide. This ""586 method is schematically illustrated in FIG. 1, where 920 ml of 92% xe2x80x9cconcentratexe2x80x9d (Part A) is mixed with 80 ml of 50% hydrogen peroxide solution (Part B) to produce 1000 ml of activated DF-100 foam solution (i.e., ready-to-use foam solution) having an ultimate hydrogen peroxide concentration of 4%.
Example 1 lists the ingredients of Part A that can be used with the ""586 method for making a DF-100 foam formulation.
18 L of deionized water (carrier)
691.2 g of WITCO ADOGEN 477(trademark) (cationic hydrotrope)
360 g of Alcohol Mix #1
36 g of JAGUAR 8000(trademark) (cationic water-soluble polymer)
10% HCL, a few ml""s, (used to adjust the pH to 6.5)
540 g of WITCO VARIQUAT 80MC(trademark) (cationic surfactant)
270 g of Alcohol Mix #2 (foam stabilizer)
900 g of potassium bicarbonate (for later reacting with H2O2 in Part B)
WITCO VARIQUAT 80MC(trademark) (cationic surfactant) is a trademarked mixture of benzyl (C12-C16) alkyldimethylammonium chlorides. WITCO ADOGEN 477(trademark) (cationic hydrotrope) is a trademarked pentamethyltallow alkyltrimethylenediammonium dichloride. JAGUAR 8000(trademark) (cationic water-soluble polymer) is a trademarked Guar Gum, 2-hydroxypropyl ether. Alcohol Mix #1 comprises a mixture of 36.4% isobutanol, 56.4% diethyleneglycol monobutylether (DEGMBE), and 7.3% dodecanol. Alcohol Mix #2 comprises a 1:1 (wt %) mixture of dodecanol and DEGMBE. The composition of Part A prepared according to Table 1 produces 20.7 liters of Part A having a concentration of 92%.
Example 2 illustrates an example of a procedure for preparing Part A from the ingredients listed in Example 1.
1. Pour 18 L of deionized H2O into large carboy with largest stir bar available.
2. Add 691.2 g of WITCO ADOGEN 477(trademark) (cationic hydrotrope). Rinse beaker used to weigh 477 w/ H2O from carboy, adding rinses back to the carboy.
3. Add 360 g of Alcohol Mix #1 (36.4% isobutanol; 56.4% DEGMBE; 7.3% dodecanol). Note the pH and continue to measure pH throughout the procedure.
4. Add 36 g of JAGUAR 8000(trademark) (water-soluble polymer). Add the JAGUAR 8000(trademark) slowly to avoid lump formation; tap in slowly from spatula. After finished adding the entire JAGUAR 8000(trademark), stir for 15 minutes. The pH should rise as the JAGUAR dissolves. Note: This is a polymer used to slightly increase the viscosity of the water, producing a more stable foam.
5. Slowly adjust the pH of the solution with drop by drop addition of 10% HCl. Adjust to pH=6.5; this only takes a few ml""s. Stir for 1 hour. The pH is lowered to solubilize the polymer. 10% HCl: 53.5 ml HCl (37.4%)+146.5 ml dH2O.
6. Add 540 g of WITCO VARIQUAT 80MC(trademark) (cationic surfactant), slowly. Note the pH (it will rise). Rinse the beaker used to weigh the VARIQUAT w/ solution from the carboy, adding rinses back to the carboy. Remove the pH probe and cover the carboy. Stir for 2 hours.
7. Add 270 g of Alcohol Mix #2, 1:1 (wt. %) dodecanol and DEGMBE, diethyleneglycol monobutylether. Add dropwise over a 1-hour period. Stir for 1 additional hour. Note final pH of foam. DEGMBE is used as a solvent for the dodecanol. Dodecanol is used to increase the surface tension w/in the laminar wall bilayer of the foam. Increased surface tension provides greater foam stability because the liquid layer between the laminar walls will not drain as fast.
8. Add 900 g of potassium bicarbonate and mix well to dissolve.
Part A can then be transported to the field, where it can be mixed with a sufficient amount of highly concentrated (30%-50%) hydrogen peroxide solution, Part B, to produce an activated DF-100 foam solution having an ultimate hydrogen peroxide concentration of 4%; made, for example, by mixing 1.8 liters of a 50% hydrogen peroxide solution (Part B) with the 20.7 liters of Part A made according to Example 2 to produce 22.5 liters of activated DF-100 foam solution.
Table 1 lists the constituents and concentrations of the activated DF-100 foam solution, made, for example, by mixing Part A from Example 1 with a sufficient amount of Part B (30-50% hydrogen peroxide solution).
The cationic surfactant can be a quaternary ammonium salt, such as cetyltrimethyl ammonium bromide. Other examples of cationic surfactants include polymeric quaternary compounds. The concentration of the quaternary ammonium salt is restricted to be no more than 10 wt % because at higher concentrations the quaternary ammonium salt becomes significantly toxic to humans and to the environment. Examples of suitable cationic hydrotropes are tetrapentyl ammonium bromide, triacetyl methyl ammonium bromide, and tetrabutyl ammonium bromide. The fatty alcohols may contain 10-16 carbon atoms (e.g., 1-dodecanol or 1-tetradecanol). The combination of bicarbonate and hydrogen peroxide forms a highly effective oxidizer (the highly reactive hydroperoxycarbonate species), which is a significant contributor to the neutralization of CBW agents. The concentration of hydrogen peroxide is restricted to no more than 10% (e.g. 4%), because higher concentrations are significantly corrosive, especially in the range of 30-50% concentration. The weight percentage ratio of surfactant to hydrotrope in Foam Solution #1 is equal to 0.8 (i.e., 2.6% divided by 3.3% equals 0.8).
Making up activated DF-100 solution using the ""586 method requires that a highly concentrated (30%-50%), highly toxic, and highly corrosive aqueous solution of hydrogen peroxide (Part B) be stored, transported, and handled.
However, if the concentration of the aqueous hydrogen peroxide solution (Part B) could be reduced to less than 8% (e.g., by diluting it with water), then it could be stored, shipped, and handled as a xe2x80x9cnon-hazardousxe2x80x9d material, without the concurrent safety and health concerns. Alternatively, Part B could be stored in a dry solid or powder form, such as urea hydrogen peroxide, and then added to a sufficient amount of water to make a safe, diluted solution of hydrogen peroxide having a concentration less than 8%. Note that the step of adding the urea hydrogen peroxide powder to water to make up Part B could also be done in the field, prior to mixing Parts A and B.
Concurrently, if the concentration of Part A could be changed from 92% (essentially unconcentrated) to about 14-25% (highly concentrated), then the size, weight, and cost of the containers used for manufacturing, and the costs for shipping, and storing the concentrate (Part A) could be significantly reduced.
Against this background, the present invention was developed.